The invention relates to an improved roof insulation structure and method of making the structure and more particularly, but not by way of limitation, to a self-supporting medium density thermal insulation blanket adapted for receipt on top of and between parallel roof purlins. The blanket forms a "U" shaped configuration for receiving a blanket of thick low density thermal insulation therein.
Heretofore there have been various types of metal building roof systems and methods of applying insulation such as the invention disclosed in U.S. Pat. Nos. 4,047,345, 4,047,346, and 3,969,863 to Alderman and U.S. Pat. Nos. 3,513,614 and 3,662,509 to Studzinski. Also various types of grooving self-supporting insulation and methods of grooving the insulation are disclosed in U.S. Pat. No. 3,958,385 to Bondra and U.S. Pat. No. 4,117,641 to Wells. Additional roof insulation systems are disclosed in U.S. Pat. No. 3,979,537 to Troyer and U.S. Pat. No. 2,864,324 to Clements.
None of the patented inventions provide means for receiving and holding low density thick blankets of insulation on top of self-supporting medium density blankets constructed to be contoured around the structure of the metal roof purlins.